The invention relates to a sliding-shaft medical instrument having a sliding shaft that has first and second slide elements, arranged side by side and displaceable relative to one another, having at least one jaw part at a distal end of the sliding shaft, that is actuable, by way of a handle at a proximal end, via a relative displacement of the first and second slide elements, the handle having two handle elements that are movable relative to one another.
A sliding-shaft instrument of this kind is known from DE-A-41 15 937.
A further sliding-shaft instrument of this kind is known from the company brochure of Karl Storz GmbH & Co., Tuttlingen, Germany, entitled "Karl Storz-Endoskope" [Karl Storz endoscopes], section entitled "Instrumente fYr Nase und Nasenplastik" [Instruments for the nose and rhinoplasty], page N 10 A.
Sliding-shaft instruments are used in endoscopic surgery for surgical operations of various kinds in the human or animal body, sliding-shaft instruments being particularly suitable for transferring large forces even in confined spaces, for example between vertebrae.
The sliding-shaft instrument known from the aforesaid company brochure has a sliding shaft that has two slide elements, arranged side by side and displaceable relative to one another. The one, immovable sliding element is joined immovably to the immovable handle element, while the other slide element is joined displaceably and directly to the movable handle element of the handle at the proximal end. Actuation of the handle causes the movable slide element to be displaced relative to the immovable slide element, so that a jaw part at the distal end of the sliding-shaft instrument can be actuated, for example to detach or grasp tissue.
A disadvantage of the known sliding-shaft instrument, however, consists in the fact that it can be disassembled into its components only inadequately, or at least only with great time expenditure, so cleaning of the sliding-shaft instrument presents difficulties. In particular, contaminants collect between the two slide elements, i.e. more precisely between the mutually contacting sliding surfaces of the two slide elements. In the known sliding-shaft instrument, the region between the slide elements is not accessible, so that it is impossible to guarantee that contaminants between the slide elements can be reliably eliminated.
In the case of longer instruments, however, especially for endoscopically assisted abdominal cavity surgery, it is absolutely necessary that the sliding-shaft instrument be easy to clean.
The sliding-shaft instrument known from the aforesaid DE-A-41 15 937 has a sliding shaft that is also directly joined to the handle. The sliding shaft is configured so that the two slide elements forming the sliding shaft can be separated from one another for easier cleaning once the sliding shaft has been taken off the handle, but this known sliding-shaft instrument is disadvantageous for the following reasons:
In endoscopically assisted operations, the necessary instruments are often inserted through a trocar which presents an opening having a circular cross section. Since a positive pressure is generated in order to make the surgical field accessible, any such instrument in the trocar must seal as tightly as possible and also be securely guided by the trocar.
The aforesaid known sliding-shaft instrument does not guarantee such sealing closure in a trocar, since the sliding shaft extends as far as the handle, and thus upon insertion into a trocar, a positive pressure that has been established in the surgical field can escape outward between the two slide elements that are arranged side by side. A further disadvantage when the known instrument is used with a trocar consists in the fact that one of the two slide elements is in frictional contact with the trocar when the instrument is actuated therein.
Also known, from DE Utility Model 94 21 125, is a surgical forceps that is not a sliding-shaft instrument as defined by the present invention, but rather a tubular-shaft instrument whose tubular shaft has a longitudinal slot in which is guided an actuation rod that is axially movable in the longitudinal slot and is joined at the distal end to a jaw part in order to move it. This tubular-shaft instrument also does not guarantee sealed closure in a trocar, since in this case a positive pressure can escape through the longitudinal slot in the tubular shaft.
A conventional tubular-shaft instrument having a closed tubular shaft is known from DE Utility Model 17 12 028, but it is not a sliding-shaft instrument.
It is therefore the object of the invention to develop a sliding-shaft instrument of the kind cited initially in such a way that it can easily be cleaned and made sterile, and so as to ensure that contaminants on the components, in particular between the slide elements, can be eliminated. An instrument of this kind is moreover intended to ensure the sealing tightness of a trocar through which it is introduced, and to be securely guided and held by the trocar.